What bit version of office are you using.

32 or 64

also is it the local version of 365 or desktop install

I got the same problem...

Having the same error using Office 365 64-bit, but it's only happening with a report that goes with a particular company.  How can I debug this report to find the problem?

It seems inconsistent.  It will write the reports to file system, but only sometimes the emails will go through.

A message from Microsoft on August 31st:

"While we will not be communicating a date when they will be turned off, customers should expect delays in sending to start later this year as we will deliberately introduce functionality that will randomly fail some percentage of the request our service receives. "

This sounded like it could be the cause of the intermittent failures sending mail for report distributions.  Sure enough I can see logs showing it's using TLS 1.0.  We're on Sage 2021, but that alone doesn't seem to be enough as you might be lead to believe after reading this announcement:

https://www.sagecity.com/us/sage100_erp/f/sage-100-announcements-news-tips/176931/sage-100-sage-100-2018-and-older-email-errors

If we're using the SMTP settings rather than the Outlook profile to distribute reports how can we enforce the use of TLS 1.2?  In the configuration there is only a checkbox to "use SSL".  TLS is essentially the replacement for SSL, but it is not using the newest version of TLS when you check that box.  It's using TLS 1.0 by default.  Is this the BI Tools Excel addon considered a .NET application that uses the system default configuration to send email?  Is that configuration defined somewhere else?

That sounds like a musical chairs response.